This invention relates to a signal recording apparatus, and more particularly is suitable to be adapted to, for example, a compact rotary head type digital audio tape recorder.
In a conventional rotary head type digital audio tape recorder (DAT) of this kind, a line input terminal 2 for inputting an audio signal from an external device to a DAT 1 is provided and a line output terminal 3 from which an audio signal is outputted to the external device is provided, as shown in FIG. 1.
Therefore, by connecting a line output terminal 6 of, for example, a cassette tape recorder with radio receiver 5 and the line input terminal 2 of the DAT 1 through a line cord 8 and connecting a line input terminal 7 of the cassette tape recorder with radio receiver 5 and the line output terminal 3 of the DAT 1 through a line cord 9, it is possible to send radio broadcasting received by the cassette tape recorder with radio receiver 5 to the DAT 1 through the line cord 8 for recording it in the DAT 1 or to output a reproduced sound from the DAT 1 from a speaker of the cassette tape recorder with radio receiver 5 through the line cord 9 by making the DAT 1 in a reproduction mode and outputting an audio signal on the line output terminal 3.
A recording and/or reproducing apparatus such as the DAT 1 and the cassette tape recorder with radio receiver 5 has, in general, a construction in which, when it is controlled to a line input mode, the audio signals inputted from the line input terminals 2 and 7 are outputted from the line output terminals 3 and 6, respectively, as they are, so that the audio signals outputted from the line output terminals 3 and 6 can be monitored by user.
Accordingly, when the DAT 1 is made to a line input recording mode while the cassette tape recorder with radio receiver 5 being controlled to a line input mode so as to monitor the recording sound of the DAT 1 by means of the speaker of the cassette tape recorder with radio receiver 5, an audio signal inputted from the Line input terminal 2 of the DAT 1 is gradually amplified by a loop formed by the line output terminal 3 of the DAT 1, the line cord 9, the line input terminal 7 of the cassette tape recorder with radio receiver 5, the line output terminal 6, the line cord 8 and the line input 2 of the DAT 1, causing an oscillation phenomenon to occur and so there was a problem that rasping oscillation sound is produced from the speaker of the cassette tape recorder with radio receiver 5.
As one method for solving this problem, it may be considered to disconnect the line cord 9 when the DAT 1 is made to the line input recording mode or other methods such as switching the line input mode of the cassette tape recorder with radio receiver 5 to another mode, etc., may be considered, however, when such method is employed, there is a problem that it is impossible to avoid user's troublesome handling and, so, it was not yet enough as solution.